Use ItemCommand in C # of a listview

I'm working with a ListView where you display the items in a cluttered list and as links . Under ListView has the "CREATE" button to insert a new item in ListView .

I was able to make, when I edit any list item by clicking the link button, the "CREATE" button is Enabled = false , I did this using ItemCommand ListView as in the code below. The problem is that I wanted to not allow the user to do an edit of another item when it is inserting a new one, any tips?

The "CREATE" button is outside of ListView .

protected void lvDiagnosticos_ItemCommand(object sender, ListViewCommandEventArgs e)
{
    if (e.CommandName == "Edit")
    {
        criarDiagnostico.Enabled = false;
    }
    else
    {
        criarDiagnostico.Enabled = true;
    }
}